Unversioned versus Shared - Sitecore

• Shared: When this checkbox is selected, the field has the same value for every numbered version in all supported languages. When the Shared property is set, changes to the field value in any language or numbered version of the item will be reflected in all the other language versions and numbered versions. In other words, the field is the same, no matter the version or language.
  

• Unversioned: When this checkbox is selected, the field has the same value for every numbered version within a language, but may have different values between languages. Unversioned fields are similar to shared fields, but the system can maintain different field values for different languages. In other words, the field is the same, no matter the version; the field depends only on language.